基于C#的ArcEngine二次开发35：缓冲区分析
目录
0 arcgis建立缓冲区
1 根据选择要素建立缓冲区并查询
1.1 代码
1.2 代码分析
2 从线要素首尾节点相邻的角度合并同名道路
几点说明：
使用ITopologicalOperation.Buffer建立缓冲区时，可能出现以下几种情况：
- 出现异常卡死现象，修改缓冲区为合适的值，即可解决；
- 不连续的要素无法建立缓冲区，此时应根据属性判断，将要素分离开来
0 arcgis建立缓冲区
缓冲区是地理空间目标的一种影响范围或服务范围，具体指在点、线、面实体的周围，自动建立的一定宽度的多边。
方法/步骤
1. 向arcmap中添加要建立缓冲区的图层。
2. 调出建立缓冲区工具。有两种方法可以调出缓冲区工具，一种是在菜单地理处理中选择缓冲区;另外一种方法是在arctoolbox中选择分析工具-邻域分析-缓冲区。
3. 首先选择输入要素，选择输出要素名字位置和缓冲区范围，融合字段可以根据需要进行设置。
4. 建立缓冲区。线图层建立缓冲区的过程中可以选择缓冲区的位置，在侧类型中可以选择缓冲区在线的左边、右边还是两边都有，末端类型可以选择末端是圆形还是方形，如图，侧类型为full，末端为round形成的缓冲区。
5. 面建立缓冲区和线一样，不过面的缓冲区侧类型只有两种：full和outside_only。full是对整个面都建立缓冲区，outside_only是在面的外面建立缓冲区。
6. 在工具箱中右击“缓冲区”可以批处理，节约时间。
END
注意事项：融合字段按作图要求进行选择，一般缓冲区都做分析用，可以不要太多属性
1 根据选择要素建立缓冲区并查询
1.1 代码
这是在其他地方找到的一段代码：
实现功能：
1.获取鼠标选中的要素
2.对选中要素设置缓冲距离，在地图上显示缓冲区
3.进行缓冲区查询，获得缓冲区内的要素，并放入TreeList展示
///
/// 创建缓冲区
///
private void CreateBuffer()
{
ITopologicalOperator pTopo = null;
IElement pElement = null;
IGeometry pBuffer = null;
IGeometry pGeo = null;
ISelection pSelection = null;
IEnumFeatureSetup pEnumFeatureSetup = null;
IEnumFeature pEnumFeature = null;
IFillSymbol pFillSymbol = null;
IRgbColor pRgbColor = null;
IFeature pFea = null;
IFeature pFeature = null;
IFeatureLayer pFeaLayer = null;
IFeatureClass pFeaClass = null;
IFeatureCursor pFeaCursor = null;
ISpatialFilter pSpatialfilter = null;
try
{
if (m_pMap != null)
{
(m_pMap as IGraphicsContainer).DeleteAllElements();
}
//// 获得选中要素
pSelection = m_pMap.FeatureSelection;
pEnumFeatureSetup = pSelection as IEnumFeatureSetup;
pEnumFeatureSetup.AllFields = true;
pEnumFeature = pEnumFeatureSetup as IEnumFeature;
pEnumFeature.Reset();
pFea = pEnumFeature.Next();
//// 遍历选中要素
while (pFea != null)
{
pGeo = pFea.ShapeCopy;
pTopo = pGeo as ITopologicalOperator;
pBuffer = pTopo.Buffer(m_dDistance);
pElement = new PolygonElementClass();
pElement.Geometry = pBuffer;
//// 设置缓冲区颜色
pFillSymbol = new SimpleFillSymbolClass();
pRgbColor = new RgbColorClass();
pRgbColor.Red = 255;
pRgbColor.Green = 255;
pRgbColor.Blue = 153;
pRgbColor.Transparency = 1;
pFillSymbol.Color = pRgbColor;
(pElement as IFillShapeElement).Symbol = pFillSymbol;
(m_pMap as IGraphicsContainer).AddElement(pElement, 0);
//// 设置空间过滤器
pSpatialfilter = new SpatialFilterClass();
pSpatialfilter.Geometry = pBuffer;
//// 遍历图层
for (int i = 0; i < m_pMap.LayerCount; i++)
{
pFeaLayer = m_pMap.get_Layer(i) as IFeatureLayer;
pFeaClass = pFeaLayer.FeatureClass;
switch (pFeaClass.ShapeType)
{
case esriGeometryType.esriGeometryPoint:
{
pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
break;
}
case esriGeometryType.esriGeometryPolyline:
{
pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
break;
}
case esriGeometryType.esriGeometryPolygon:
{
pSpatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;
break;
}
}
pSpatialfilter.GeometryField = pFeaClass.ShapeFieldName;
pFeaCursor = pFeaClass.Search(pSpatialfilter, false);
pFeature = pFeaCursor.NextFeature();
TreeListNode tlNode = null;
//// 查询到的要素添加到TreeList
while (pFeature != null)
{
//// 添加图层节点到TreeList
bool bIsContainLayer = false;
foreach (TreeListNode node in tlResult.Nodes)
{
if (node.GetDisplayText(0).Equals(pFeaLayer.Name))
{
tlNode = node;
bIsContainLayer = true;
break;
}
}
if (!bIsContainLayer)
{
tlNode = tlResult.AppendNode(new object[] { pFeaLayer.Name }, null);
}
//// 添加要素到图层节点下
bool bIsAdd = false;
foreach (TreeListNode childnode in tlNode.Nodes)
{
if (childnode.GetDisplayText(0).Equals(pFeature.OID.ToString()))
{
bIsAdd = true;
break;
}
}
if (!bIsAdd)
{
tlResult.AppendNode(new object[] { pFeature.OID, GtMap.GxAEHelper.Feature.GetValue(pFeature, "NAME") }, tlNode);
}
pFeature = pFeaCursor.NextFeature();
}
}
pFea = pEnumFeature.Next();
}
IActiveView pActiveView = m_pMap as IActiveView;
pActiveView.Refresh();
}
catch (Exception ex)
{
}
}
1.2 代码分析
获取要素图形：
IGeometry pGeo = pFea.ShapeCopy;
将图形要素跳转为ITopologicalOperator接口
ITopologicalOperator pTopo = pGeo as ITopologicalOperator;
在拓扑空间建立缓冲区
IGeometry pBuffer = pTopo.Buffer();
2 从线要素首尾节点相邻的角度合并同名道路
1 using System;
2 using System.Collections;
3 using System.Collections.Generic;
4 using System.Text;
5 using System.IO;
6 using System.Windows.Forms;
7 using ESRI.ArcGIS.ArcMapUI;
8 using ESRI.ArcGIS.Carto;
9 using ESRI.ArcGIS.Geodatabase;
10 using ESRI.ArcGIS.Geometry;
11
12 namespace MergeDisconnectPolylineAddin
13 {
14 public class MergePolyline : ESRI.ArcGIS.Desktop.AddIns.Button
15 {
16
17 IMap map = null;
18 IActiveView pActiveView = null;
19 //private List DisconnPolylineList = new List();
20
21 public MergePolyline()
22 {
23 IMxDocument mxDoc = ArcMap.Application.Document as IMxDocument;
24 map = mxDoc.FocusMap;
25 pActiveView = mxDoc.ActivatedView;
26 }
27
28 protected override void OnClick()
29 {
30 //
31 // TODO: Sample code showing how to access button host
32 //
33 ArcMap.Application.CurrentTool = null;
34
35 //计算程序耗时
36 DateTime beforDT = System.DateTime.Now;
37
38 List distinctString = getDistinctNAMEValue();
39 MergePloyline(distinctString);
40
41 DateTime afterDT = System.DateTime.Now;
42 TimeSpan ts = afterDT.Subtract(beforDT);
43 MessageBox.Show("线要素合并结束，运行程序共耗时约："+ ts.Minutes+"分钟");
44 }
45
46 public List getDistinctNAMEValue()
47 {
48 IFeatureLayer featureLayer = map.get_Layer(0) as IFeatureLayer;
49 IFeatureClass featureClass = featureLayer.FeatureClass;
50 IQueryFilter queryFilter = new QueryFilterClass();
51 queryFilter.WhereClause = "";
52 IFeatureCursor pFeatCursor = featureClass.Search(queryFilter, false);
53 IFeature pFeature = pFeatCursor.NextFeature();
54 ArrayList fieldArray = new ArrayList();
55 List distinctString = new List();
56 while (pFeature != null)
57 {
58 if (featureClass.ShapeType == esriGeometryType.esriGeometryPolyline)
59 {
60 IFields fields = pFeatCursor.Fields;
61 int fieldIndex = fields.FindField("NAME");
62 string field_NAME = (string)pFeature.get_Value(fieldIndex);
63 fieldArray.Add(field_NAME);
64 }
65 pFeature = pFeatCursor.NextFeature();
66 }
67 distinctString = removeSameString(fieldArray);
68 return distinctString;
69 }
70
71 public void MergePloyline(List DistinctNameValue)
72 {
73 IFeatureLayer featureLayer = map.get_Layer(0) as IFeatureLayer;
74 IFeatureClass featureClass = featureLayer.FeatureClass;
75
76 //IDataset dataset = featureClass as IDataset;
77 //IWorkspaceEdit workspaceEdit = dataset.Workspace as IWorkspaceEdit;
78 //Type.Missing指的是空类型，因为有些方法你传null给它会出错的，必须要用Type.Missing.
79 object Missing = Type.Missing;
80 //workspaceEdit.StartEditing(true);
81 //workspaceEdit.StartEditOperation();
82 //string field_NAME = "";
83
84 for (int i = 0; i < DistinctNameValue.Count; i++)
85 {
86 IQueryFilter queryFilter = new QueryFilterClass();
87 queryFilter.WhereClause = "";
88 IFeatureCursor pFeatCursor = featureClass.Search(queryFilter, false);
89 IFeature pFeature = pFeatCursor.NextFeature();
90
91 IFeature pFeatureFirst = pFeature;
92 //List toMergePolylineList = new List();
93
94 IGeometryCollection Geometrybag = new GeometryBagClass();
95 ITopologicalOperator2 pTopOperatorFirst = null;
96 IGeometry geometrySecond = null;
97 IGeometry pGeometryFirst = null;
98 bool bSwitch = true;
99 while (pFeature != null)
100 {
101 map.SelectFeature(featureLayer, pFeature);
102 if (featureClass.ShapeType == esriGeometryType.esriGeometryPolyline)
103 {
104 //IPolyline polyline = geometry as IPolyline;
105 IFields fields = pFeatCursor.Fields;
106 int fieldIndex = fields.FindField("NAME");
107 string field_NAME = (string)pFeature.get_Value(fieldIndex);
108
109 if (field_NAME == DistinctNameValue[i])
110 {
111 if (bSwitch)
112 {
113 //将当前name字段相同的feature中的第一个feature传给pFeatureFirst
114 pFeatureFirst = pFeature;
115 pGeometryFirst = pFeature.Shape;
116 pTopOperatorFirst = (ITopologicalOperator2) pGeometryFirst;
117 pTopOperatorFirst.IsKnownSimple_2 = false;
118 pTopOperatorFirst.Simplify();
119 pGeometryFirst.SnapToSpatialReference();
120 bSwitch = false;
121 //break;
122 }
123 else
124 {
125 //geometrySecond = pFeature.ShapeCopy;
126 geometrySecond = pFeature.Shape;
127 Geometrybag.AddGeometry(geometrySecond, ref Missing, ref Missing);
128 //toMergePolylineList.Add(polyline);
129 }
130 }
131 //DisconnPolylineList.Add(polyline);
132 }
133 pFeature = pFeatCursor.NextFeature();
134 }
135 IEnumGeometry tEnumGeometry = (IEnumGeometry)Geometrybag;
136 //IGeometry mergeGeomery = null;
137 pTopOperatorFirst.ConstructUnion(tEnumGeometry);
138
139 pTopOperatorFirst.IsKnownSimple_2 = false;
140 pTopOperatorFirst.Simplify();
141 pFeatureFirst.Shape = pGeometryFirst;
142 //pFeatureFirst.Store();
143 IFeatureLayer featureLayer2 = map.get_Layer(1) as IFeatureLayer;
144 IFeatureClass featureClass2 = featureLayer2.FeatureClass;
145 AddPolyline(featureClass2, pGeometryFirst);
146 }
147 //workspaceEdit.StopEditOperation();
148 //workspaceEdit.StopEditing(true);
149 }
150 private void AddPolyline(IFeatureClass pFeatureClass, IGeometry polyline)
151 {
152 IFeatureBuffer featureBuffer = pFeatureClass.CreateFeatureBuffer();
153 IFeatureCursor featureCursor;
154 featureCursor = pFeatureClass.Insert(true);
155 featureBuffer.Shape = polyline;
156 featureCursor.InsertFeature(featureBuffer);
157 featureCursor.Flush();
158 System.Runtime.InteropServices.Marshal.ReleaseComObject(featureCursor);
159 }
160 public List removeSameString(ArrayList stringArray)
161 {
162 //List用于存储从数组里取出来的不相同的元素
163 List distinctString = new List();
164 foreach (string eachString in stringArray)
165 {
166 if (!distinctString.Contains(eachString))
167 distinctString.Add(eachString);
168 }
169 return distinctString;
170 }
171
172 protected override void OnUpdate()
173 {
174 Enabled = ArcMap.Application != null;
175 }
176 }
177
178 } X 问题及处置办法
X.1 HRESULT:0x80040215
在使用ITopologicalOperator求交集等操作的时候，有时会出现“ HRESULT:0x80040215”这个异常
原因是空间参考不一样所致。
将 SpatialReference 属性设为同一空间参考就不会出现 HRESULT:0x80040215 异常啦。